3 December 2008 MAR 110 Lecture 32 Warming, Sea Ice Melting, and Sea Level 1MAR110 LECTURE #32 Global Warming, Sea Ice & Sea Leve Late 19Late 19ththCentury Melting of Little Ice Age IceCentury Melting of Little Ice Age IceErnest Ernest ShackletonShackletonExplores Explores Antarctica 1915Antarctica 1915The Titanic takes The Titanic takes an April 1912 an April 1912 “Cruise”“Cruise”Figure 32.2 The Little Ice Age Transitions to Warming The Little Ice Age ( ~1350 to 1850) abruptly transitioned to a warming trend that persists to present day. The large amounts of polar region ice that accumulated during the Little Ice Age, began to break up, creating expanded fields of icebergs. The Titanic disaster occurred because of the reduced respect for the ice. The less permanent ice in and around Antarctica sparked a race to the South Pole (ItO)PostPost--GlaciationGlaciationWarmingWarmingFigure 32.1 Post Glaciation Northern Hemisphere Warming (XXXX)3 December 2008 MAR 110 Lecture 32 Warming, Sea Ice Melting, and Sea Level 2 Figure 32.3a North Atlantic Sea Ice Icebergs populated the North Atlantic trade routes in April 1912 (??) Figure 32.3b Titanic’s Fateful Cruise The path of the Titanic before it sank after hitting an ice berg 14 April 1912. (??)3 December 2008 MAR 110 Lecture 32 Warming, Sea Ice Melting, and Sea Level 3 Figure 32.5 Global Warming Continues to Present Day (NG 3-98) Figure 32.4 Endurance Trapped in the Antarctica Ice In a 1916 attempt to be the first human to reach the South Pole (by land), Ernest Shackleton expeditionary ship –the Endurance - got caught in the ice surrounding Antarctica. Shackleton’s exploits are documented in his book entitled “South” (ES)3 December 2008 MAR 110 Lecture 32 Warming, Sea Ice Melting, and Sea Level 4 “Recent” WARMING is a FACT“Recent” Carbon Dioxide increase is a FACTARE THEY RELATED?Figure 32.7 Evidence of Global Warming & CO2 Increase (NG 3-98) EVIDENCE of WARMINGEVIDENCE of WARMINGFigure 32.6 Evidence of Global Warming (NG 3-98)3 December 2008 MAR 110 Lecture 32 Warming, Sea Ice Melting, and Sea Level 5 The The Greenhouse Greenhouse EffectEffectAnalogyAnalogyEarthEarth’’ssLong Wave Long Wave RadiationRadiation..trapped by..trapped by““Greenhouse Greenhouse GasesGases””Figure 32.9 Analogy: Greenhouse Warming (NG 3-98) EarthEarth’’s s Long Wave Infrared RadiationLong Wave Infrared Radiation..trapped by ..trapped by ““Greenhouse GasesGreenhouse Gases””Figure 32.8 Fundamentals of Global Warming & CO2 Increase (NG 3-98)3 December 2008 MAR 110 Lecture 32 Warming, Sea Ice Melting, and Sea Level 6 No matter the causeGLOBAL WarmingHAS CONSEQUENCES !Sea Level Rise is one of themQUESTIONS regarding GLOBALWARMINGHow much is due to: ….a “LONGER-TERM” NATURAL CYCLE ?……..HUMAN ACTIVITIES ?Figure 32.10 Global Warming Causes & Consequences? (NG 3-98) The Last 20,000 Years The Last 20,000 Years Global Sea Level RiseGlobal Sea Level RiseFigure 32.11 Coastline Changes Due to Sea Level Rise Florida During the past 20,000 years sea level rise has changed the coastlines of Florida and SE Asia. (ItO)3 December 2008 MAR 110 Lecture 32 Warming, Sea Ice Melting, and Sea Level 7 THE ARCTIC ICETHE ARCTIC ICESubmarine Trip Submarine Trip Under Arctic Ice CoverUnder Arctic Ice CoverFigure 32.13 Northern Hemisphere Ice Cover (upper panel) People have been looking for a northern ocean route to Asia for hundreds of years. However, persistent Arctic sea ice has foiled those plans. Except for submarines (the Nautilus in this 1958 case) ships have been unable to traverse the region. However the size of the Arctic ice pack is thinning. (NG). LOOKING LOOKING forforan ARCTIC an ARCTIC SHIPPING SHIPPING LANE:LANE:1500 1500 Figure 32.12 Northern Hemisphere Ice Cover (upper panel) People have been looking for a northern ocean route to Asia for hundreds of years. However, persistent Arctic sea ice has foiled those plans..3 December 2008 MAR 110 Lecture 32 Warming, Sea Ice Melting, and Sea Level 8 Figure 32.14 Sea Ice and Climate (O)3 December 2008 MAR 110 Lecture 32 Warming, Sea Ice Melting, and Sea Level 9 Figure 32.16 Recent Sea Level Change Between 1992 and 2002 global sea level rose at an accelerating rate about 20 millimeters (2 cm ~ 1 inch) per decade. The melting of land-grounded ice is contributing to this rise. NA Ice NA Ice Cover Cover EvolutionEvolution1979197920032003Figure 32.15 Northern Hemisphere Ice Cover Evolution (upper panels) Receding glacial ice cover - 21 to 14 ky BP. (lower panels) In recent decades, arctic ice has been melting at an increasingly more rapid rate during summer and has not been regenerated during the winter. Note the change from 1979 to 2003. Greenland ice is of particular concern because melting of its land-based ice will contribute to sea level rise (NG ??).3 December 2008 MAR 110 Lecture 32 Warming, Sea Ice Melting, and Sea Level 10 IF …IF …the TOTAL the TOTAL AntarcticAntarctic& & Greenland Greenland Ice Cover Ice Cover Melted,Melted,THEN..THEN..CatastropicCatastropicSeaSeaLevel Level Rise!Rise!Figure 32.18 Catastrophic Sea Level Rise Antarctic Antarctic Ice Cover Ice Cover EvolutionEvolutionearlyearly20022002Larson Ice Shelf CollapseLarson Ice Shelf CollapseOneOneMonthMonthLaterLaterSeasonalSeasonalEvolutionEvolutionFigure 32.17 Ice Melting and Sea Level Change Between 1992 and 2002 global sea level rose at an accelerating rate about 20 millimeters (2 cm ~ 1 inch) per decade. The melting of land-grounded ice is contributing to this rise.3 December 2008 MAR 110 Lecture 32 Warming, Sea Ice Melting, and Sea Level 11 Figure 32.2 Ice Cover During the last major Glaciation 20ky BP Thick Ice overran significant portions of North America and Northern Eurasia. (XXXX) Global Sea Level RiseGlobal Sea Level RiseFuture? Future? Figure 32.19 Future Florida Coastline?3 December 2008 MAR 110 Lecture 32 Warming, Sea Ice Melting, and Sea Level 12 Figure 32.3 Ice Cover during the last major Glaciation 20ky BP. At the height of the last major glaciation, significant portions of North America and Northern Eurasia were covered with thick ice. (XXXX) MultipleMultiple--GlaciationsGlaciations--Past 450,000 yearsPast 450,000 yearsIce Ice Formation Formation Lowers Lowers Sea LevelSea LevelFigure 32.1 Multiple-Glaciations During The Past 450,000 years The fresh component of seawater is converted to glacial ice. Thus